There is a case that data stored in a storage device such as an SSD (Solid State Drive) is lost because of trouble, wrong operation, or the like. For restoration of lost data, backup, which is to copy data stored in a storage device into another storage device at predetermined timing, is performed in general (e.g., see Patent Document 1). Thus, even if the stored data is lost because of trouble, wrong operation, or the like, it is possible to restore the lost data by using the copy data stored in the other storage device.
For updating data on an SSD, there is a need to once erase data and then write update data onto the SSD. Because storage elements deteriorate every time data is written in and erased, the life of an SSD may become short in a case where data is frequently written in and erased. Thus, a technique of wear leveling, which is to distribute data writing or the like as evenly as possible to the storage elements of an SSD, is utilized for SSDs (e.g., see Patent Document 2).    [Patent Document 1] Japanese Unexamined Patent Application Publication No. JP-A 2007-233961    [Patent Document 2] Japanese Unexamined Patent Application Publication No. JP-A 2005-316793    Patent Document 1 describes a technique of storing management information including the version number of a backup job of previous backup, deciding data to be backed up based on the stored management information, and performing backup of data.
According to the technique described in Patent Document 1, there is a need to generate and manage management information in addition to executing a data backup process. Therefore, the technique described in Patent Document 1 requires update of the management information at the time of backup, and has a problem of increase of load relating to backup using an SSD.